Agricultural harvesters such as combines are typically equipped with a harvesting header. Corn headers are specifically designed to pick corn and vary in size from two-row units to twelve-row units or more. As the harvester moves through the field, each row-unit passes between rows of corn. Corn header row units typically use gathering chains to convey crop material and ears rearward toward a cross auger. A set of driven snap rolls, which rotate based on the speed of the harvester, grabs the corn stalks and forces them downward between stripper plates. The ears of corn are snapped free of the stalk and the cross auger passes the ears to the feeder housing of the harvester. If the snap rolls are operated too fast or too slow, ears of corn may be lost or entire corn stalks may be passed to the cross auger and feeder housing.
Known row units require two gathering chains and two tensioners which are heavy, expensive and wear out easily. Furthermore, the gathering chains create a complicated drive mechanism because the axes of the drive sprockets driving the chains are at right angles to the axes of the snap rolls. Also, the gathering chains do not effectively convey a large mass of crop in conditions when material other than ears of corn, such as stalks and leaves, are severed from the ground. What is needed is a simpler and more cost effective row unit that is capable of conveying a large mass of crop.